In electrostatographic or xerographic printing processes, a photosensitive imaging member such as a charge receptive belt or cylinder surface is uniformly charged by a corona unit, a charged contact roller, or an array of light emitting diodes. The uniformly charged photoreceptor or charge receptor surface is then image-wise exposed to a light image of an original document to be copied, or a scanned laser image produced by image data acting on a laser source. The light dissipates charge at exposed portions of the photoconductor surface to record on the charge receptor surface an electrostatic latent image that corresponds to informational areas of the original document to be copied.
After the latent image is recorded on the photoreceptor, the latent image is developed by causing toner particles to adhere electrostatically to the charged portions of the photoreceptor surface forming a toner image in charged area development systems, or causing toner particles to adhere electrostatically to discharged portions of the photoreceptor in discharged area development systems. The developed toner image is subsequently transferred to a sheet using electrostatic forces, and fixed or fused using heat and pressure or radiant fusing to melt and bond toner particles into the sheet. The charge receptor may then be cleaned by removing, for example, used toner particles from a surface thereof.
Typically, the charge receptor may be a photoreceptor or rotatable metal drum having a charge-retentive surface formed of materials including silicon, amorphous selenium or its alloys, and/or other photoconductors. In the development step, the photoreceptor is presented with marking material such as developer, a mixture of toner particles and larger, typically iron, reusable carrier particles. The carrier particles have a coating. The coated carrier and toner generate a triboelectric charge separation when agitated, i.e., electron transfer between the coated carrier and toner occurs, causing the carrier to carry a net positive charge and the toner to carry a net negative charge, or vice versa. A magnetic roll or developer roll is used to apply toner particles to a surface of the photoreceptor. The toner particles have a charge that is opposite in polarity to the charge of the latent image recorded on the photoreceptor. The photoreceptor attracts the toner particles to form a visible image on the photoreceptor surface. A bias voltage may be applied to the developer roll to control the attractive forces between the toner and photoreceptor.
In related art systems, the charge receptor and developer roll are disposed in a first housing. The first housing defines an input and an output, and is configured to contain developer that is delivered from a second developer supply housing that defines a single opening that communicates with the first housing input. The first housing input may be, for example, disposed above the output when the first housing is installed in a printing system. The second housing may be configured so that when the second housing is engaged with the first housing, the single opening is arranged at a bottom portion of the second housing so that developer contained by the engaged second housing is enabled to fall through the single opening, and into the first housing through the first housing input. The magnetic roll may acquire charged toner and carrier particles, and as the magnetic roll rotates, cause toner particles to detach from carrier particles located on a surface of the magnetic roll and adhere to the portions of the charge receptor surface for producing a toner image thereon. Developer is typically caused to move from the first housing inlet to the photoreceptor in a generally horizontal direction in related art systems.
After the development step, a subsequent toner image transfer step, a separation or detack step, and a step of fixing or fusing of the toner image to a sheet, the charge receptor is cleaned in a cleaning step. Remaining toner that did not transfer to media during the transfer step may be removed from the photoreceptor by a cleaning blade or rotatable brush, for example. A reclaim system may be used to reclaim toner. In a typical reclaim system, captured toner is routed back into the first housing. A reclaim output is typically located above a reclaim input or dispense output.